Method of characterizing the effectiveness of baseoil additives

ABSTRACT

A process for preparing a baseoil blend of predetermined coking tendency, and for measuring the effectiveness of additives for reducing coking tendency in baseoils, utilizing the relationship of the content of volatile fractions and low boiling fractions in baseoil to the onset and/or progression of asphaltene formation.

This is a division of application Ser. No. 876,460, filed June 20, 1986,now U.S. Pat. No. 4,897,176.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a process for preparing a blend of baseoilshaving a predetermined coking tendency, as well as to baseoil blendsproduced thereby. The invention further relates to a process forcharacterizing the effectiveness of baseoil additives used to reducebaseoil coking tendency.

2. Description of Background Materials

A number of standardized procedures exist for determining the cokingtendencies of oils.

U.S. Pat. No. 3,248,327 discloses one test known as the Coker DetergencyTest. This test is a modification of the Pratt and Whitney Test asdescribed in United States Air Force Military Specification MIL-L-7808A.The test involves splashing the test oil in an air atmosphere against aheated aluminum panel for a given period of time and thereafterdetermining the amount of deposit formed on the panel. The oil issplashed onto the underside of an aluminum panel, and after a set periodof time the test is stopped, and the aluminum panel is washed to removeexcess non-coked oil. It is assumed that any increase in weight of thepanel, after washing and drying, must be due to coke formation on thealuminum.

A similar technique is disclosed in U.S. Pat. Nos. 3,095,377 and3,153,622, and is identified as a Panel Coker Test meeting United StatesAir Force specification MIL-L-9236A.

Yet another test is disclosed in U.S. Pat. Nos. 2,812,319 and 2,716,089,in which oil is heated and stirred in an aluminum measuring cup for aset period of time, after which the heated oil is permitted to settlewithout stirring. Thereafter the cycle is repeated a number of times,after which the oil is poured out of the cup, and the cup weighed todetermine any .increase in weight which would be indicative of coking.

Despite providing information as to the amount of coke which is formed,the above techniques are by their very definition imprecise and clumsy.These tests are subject to inconsistent results because of the numerousmechanical manipulations which are involved. Furthermore, none of theabove techniques relies upon the measurement of asphaltenes as being anindicator of the coking tendencies of lubricating baseoils, but ratherrely only upon the direct measurement of coke deposits.

SUMMARY OF THE INVENTION

One embodiment of the invention is broadly directed to a process forpreparing a baseoil blend having a predetermined coking tendency, by:

(a) measuring the amount of volatile fractions, or low boilingfractions, or both, in each of the baseoils comprising the blend, todetermine the onset and/or progression of asphaltene formation in eachof these baseoils; and

(b) blending at least two of the baseoils in relative proportionsnecessary to produce a blend having the desired coking tendency.

This embodiment may further include the step of measuring the amount ofvolatile fractions, or low boiling fractions, or both, present in theblend, for the purpose of determining the onset and/or progression of C₇-asphaltene formation.

The asphaltene for which onset and/or progression of formation isdetermined is, most preferably, C₇ -asphaltene.

Step (a) can be carried out as to the volatile fractions by:

I. heating, to approximately 600° C., or to approximately 1,000° C., asample of each of the baseoils, each sample comprising approximately0.005 to 1.0g of baseoil, in a thermal balance and under an inertatmosphere, at a rate of approximately 5° to 20° C./min. or, morepreferably, 10° C./min.; and

II. continuously measuring the weight loss in each of the samples.

Step (a) can be carried out as to the low boiling fractions by gaschromatographic distillation.

These same means for measuring the volatile fractions and low boilingfractions can also be employed in the previously mentioned additionalstep for determining the coking tendency of the blend.

A second embodiment of the invention is broadly directed to a processfor measuring the effectiveness of an additive for reducing the onsetand/or progression of asphaltene formation in a baseoil, by:

(a) measuring the amount of volatile fractions, or low boilingfractions, or both, present in the baseoil to determine onset and/orprogression of asphaltene formation in the absence of the additive;

(b) incorporating the additive into a sample of the baseoil, andcharacterizing its coking tendency by:

I. subjecting the sample to conditions which accelerate asphalteneformation in the baseoil; and

II. testing for the onset and/or progression of asphaltene formation inthe sample as a function of time; and

(c) comparing the onset and/or progression of asphaltene formation insteps (a) and (b).

The previously discussed means for measuring volatile fractions and lowboiling fractions can also be employed in this embodiment of theinvention to determine the onset and/or progression of asphalteneformation in the absence of the additive.

Asphaltene formation can be accelerated in step (b) by any of severalmeans.

One means comprises oxidizing and heating the baseoil, preferably bycontinuous oxidation at approximately 240°-360° C.

A second means for accelerating asphaltene formation is catalyticreaction of the baseoil. Any suitable catalyst, such as a Friedel-Craftcatalyst, may be employed. The preferred catalyst is selected from thegroup consisting of ferric chloride hexahydrate, cobalt octoate, ironnaphthenate, stannic chloride, and mixtures thereof. Most preferably,this catalytic reaction is carried out at a temperature of 180°-280° C.

A third means for accelerating asphaltene formation comprises reactingthe baseoil with a material selected from a group consisting ofperoxides, hydroperoxides, oxidized lube oils, and mixtures thereof. Anyof these materials can also be added in the previously discussedcatalytic reaction.

Any of these means for accelerating asphaltene formation can furtherinclude sparging the baseoil with an oxidizing gas selected from thegroup consisting of air, oxygen, ozone, nitrogen oxides (includingnitric oxide), sulfur oxides, and mixtures thereof; preferably, thebaseoil is sparged with air at 1-10 standard cubic feet of air per hour.Most preferably, a mechanical agitator is used to agitate the baseoilduring this sparging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the progression of asphaltene formation in a baseoilas a function of time at constant temperature;

FIG. 2 comparatively illustrates the amounts of asphaltene as determinedby gas-chromatographic distillation formed in different baseoils duringoxidation, also as a function of time at constant temperatures

FIG. 3 comparatively illustrates the volatilization characteristics ofdifferent baseoils in gas-chromatographic distillation as a function oftemperature;

FIG. 4 comparatively illustrates the progressive weight loss indifferent baseoils at a rate of 10° C./min. from room temperature to500° C. under nitrogen atmosphere as determined by thermogravimetricanalysis;

FIG. 5 illustrates the relationship of low boiling fractions, asdetermined by gas chromatographic distillation, to onset and/orprogression of asphaltene formation in baseoils;

FIG. 6 illustrates the relationship of volatile fractions as determinedby thermogravimetric analysis to onset and/or progression of asphalteneformation in baseoils;

FIG. 7 illustrates the thermogravimetric analysis of asphaltene; and

FIG. 8 illustrates the acceleration in onset and/or progression ofasphaltene formation as a function of the temperature to which thebaseoil is heated.

DETAILED DESCRIPTION OF THE INVENTION

Analysis of used lube oils from engine tests and- the carbonaceousmaterials from engine piston walls indicates that these materials havevery high oxygen content. 2-3 wt.% of oxygen was found in the used lubeoils, and 25-35 wt.% of oxygen was found in the carbonaceous material onthe piston walls.

High oxygen content in the oil and the carbonaceous material indicatesthat oxidative-polymerization of the baseoils is responsible for theformation of the carbonaceous material in the lube oil and thedeposition on the wall of the piston.

Further investigation of the mechanism of the carbon formation in lubeoils led to the discovery that, on air oxidation of a baseoils,paraffin-insoluble compounds-asphaltenes- are the first molecularspecies formed in baseoils upon oxidation, and that these asphaltenesare transformed gradually into carbonaceous material containing highinfusable coke (quinoline insolubles). Amongst the wide range ofparaffin insolubles which are formed upon heating and oxidation, theheptane insolubles, hereinafter designated as C₇ -asphaltenes, are ofparticular interest.

Asphaltenes generally are composed of carbon, hydrogen, oxygen, andsulfur, with a C:H atomic ratio of 1.0-1.5, and an average molecularweight of about 250-1,000. They are brownish solids with melting pointsof 100°-400° C,, with extremely high tendency to coke formation at200°-300° C. in a non-oxygen nitrogen atmosphere, with a coke yield of35-55% over 2 hrs. The asphaltenes have a decomposition temperature ofabout 400° C. as determined by thermogravimetric analysis in nitrogen.

During oxidative-polymerization of the baseoil at high temperatures,e.g., 240°-360° C,, portions of the baseoils will react with oxygen,leading to polymerization and introduction of various oxygen functionalgroups, such as phenolic, hydroxyl, carboxyl, ketones, aldehydes,ethers, etc. Other polar atoms such as sulfur and nitrogen are alsopresent. These high molecular weight, highly oxidized molecules becomeinsoluble in aliphatic solvents, and can be determined quantitatively asthe insolubles in paraffinic solvents. This insoluble portion isreferenced herein as asphaltenes.

The carbonization of asphaltenes into various carbonaceous products andcoke is known; for example, see U.S. Pat. No. 4,518,483, the disclosureof which is hereby incorporated by reference thereto, which teaches aprocess for carbonizing asphaltenes into carbon precursors useful forcarbon fiber production.

The C₇ -asphaltene formed during the oxidation of lube baseoil isdefined as the insolubles in paraffinic solvents, and, morespecifically, the insolubles in n-heptane. Therefore, asphaltenesrepresent a solubility class of compound.

One method of characterizing asphaltenes is by thermogravimetricanalysis (TGA). The thermogram of our C₇ -asphaltenes is presented inFIG. 7 (showing maximum decomposition at about 400° C.).

Asphaltenes may be specified with reference to the particular paraffinsin which they are insoluble, e.g., n-heptane, n-hexane, n-pentane,isopentane, petroleum ether, etc. For purposes of this application,particular reference is made to C₇ -asphaltenes as being the preferredindicator for coke characterization purposes.

The formation, in an initially asphaltene-free baseoil (150BS), of C₇-asphaltene and quinoline insolubles (coke) on subjecting the baseoil toair-oxidation at 360° C. (oil temperature) is illustrated graphically inFIG. 1. The transition from lube baseoil to substantially asphaltene(about 75%) prior to the onset of coke formation should be noted.

As further proof of the relationship between asphaltene and coking,reference is made to FIG. 8, in which it is seen that, as temperatureincreases, the onset of asphaltene formation, as is the case with cokeformation, is accelerated.

Regarding C₇ -asphaltene formation in baseoil oxidation, it has beendiscovered that the content of volatile fractions and/or low boilingfractions in the baseoil is directly related to asphaltene formation.Both embodiments of the invention are based upon the discovery of thisrelationship. In the first embodiment, this relationship is employed ina novel process for preparing a baseoil blend of predetermined cokingtendency; in the second, it is the basis for a novel process formeasuring the effectiveness of an additive for reducing the onset and/orprogression of asphaltene formation in baseoil.

It is noted that the techniques of gas-chromatograph distillation andthermal analysis to measure boiling and volatilization rate,respectively, are standard methods of characterization. The novelty ofthe invention lies in the discovery of the relationship between thepresence of volatile fractions and low boiling fractions in baseoilswith the rate of C₇ -asphaltene formation. It is the discovery of thisrelationship which allows for the new and unobvious processes forpreparing baseoil blends of predetermined coking tendency, and fordetermining the effectiveness of additives for reducing the onset and/orprogression of such asphaltene formation.

Basically, the inventive method of the first embodiment of thisinvention, for preparing the baseoil blend of predetermined cokingtendency, involves two steps:

a. Measuring the amount of volatile fractions, or low boiling fractions,or both, present in each of the baseoils to be blended, in order todetermine the onset and/or progression of asphaltene formation in eachof the baseoils; and

b. Blending at least two of the baseoils in the proper proportions forproducing the blend of the desired coking tendency.

The volatile fractions present in the baseoils are quantitativelymeasured by means of thermal analysis, which measures the volatilesproduced at 100° C.-600° C. Gas-chromatographic distillation is employedto quantitatively measure the presence of low boiling fractions.

A standard thermal balance is used for measuring the volatile fractions.A small quantity, approximately 0.005 to 1.0 grams, of a baseoil isheated in the thermal balance under nitrogen atmosphere from roomtemperature to 600° C., at a heating rate of from approximately 5°C./min. to 20° C./min. The most preferred heating rate is 10° C./min.,for the reason that this rate provides a well-defined thermogram. Duringthe heating, the weight loss occurring due to volatilization anddecomposition of the baseoil is recorded continuously as a function oftime.

Alternatively, the baseoil can be heated to 1,000° C. at the indicatedheating rate, in either an inert or an oxidizing atmosphere.

Gas-chromatographic distillation (GC-D), is employed to measure thepresence of low boiling fractions. A small sample of baseoil is injectedinto a chromatographic column. This column is then heated, and theboiling characteristics of the baseoil fractions are recorded.

These techniques of thermal analysis and gas-chromatograhic distillationcan be applied to each of the baseoils which might be added to theblend. The resulting measurements can are used to determine the onsetand/or progression of asphaltene formation in each of these baseoils.This information is subsequently used to determine the relativeproportions of the baseoils to combine in order to produce a blendhaving the desired coking tendency. The relationship of baseoil lowboiling fractions and volatile fractions to asphaltene formation, andtherefore to coking tendency, is illustrated in the following examples.

EXAMPLES 1-4 Asphaltene Formation in Untreated Baseoil

Four baseoils obtained by vacuum distillation of vacuum residues areoxidized at 300° C. The asphaltene content is determined on samplesobtained hourly and analyzed. The rate of C₇ -asphaltene formationvaries depending on the type of baseoil used.

The results of this procedure are indicated in Table 1 below.

                  TABLE I                                                         ______________________________________                                                 Example 1 Example 2 Example 3                                                                             Example 4                                Oxidation                                                                              Baseoil   Baseoil   Baseoil Baseoil                                  Time (hours)                                                                           (100 N)   (150 LP)  (600 N) (150 BS)                                 ______________________________________                                        1        0                                                                    2         1.3      0                                                          3         9.0       2.5                                                       4        22.8      13.4                                                       5        35.3      31.7                                                       6        43.0      43.0      0                                                7                             0.9                                             8                             6.6    0                                        9                            14.8     0.4                                     10                           28.2     5.0                                     11                           40.5    12.0                                     12                                   18.0                                     13                                   --                                       14                                   33.0                                     15                                                                            16                                                                            ______________________________________                                    

FIG. 2 graphically illustrates the results for Examples 1, 2, 3, and 4.

EXAMPLES 5-8 Gas-Chromatographic Distillation (GC-D) Characteristics ofBaseoils

Four lube baseoils are injected into a gas-chromatographic distillationunit and their distillation characteristics are thereafter determined.

FIG. 3 illustrates the results of this characterization for Examples 5,6, 7, and 8 for the four baseoils, 100N, 150BS, 600N, and 150LP,respectively.

EXAMPLES 9-12 Volatilization Characteristics of Baseoils byThermogravimetric Analysis

Four baseoils are heated in a thermal balance, under nitrogen atmosphere(1.0 liter-min.), at a rate of 10° C./min., from room temperature to500° C. The resulting weight loss at each temperature increment due tovolatilization was automatically recorded, and is presented in Table IIbelow.

                  TABLE II                                                        ______________________________________                                                 Example 9 Example 10                                                                              Example 11                                                                            Example 12                               Temperature                                                                            Baseoil   Baseoil   Baseoil Baseoil                                  (°C.)                                                                           100 N     150 LP    600 N   150 BS                                   ______________________________________                                        150      1.0       0         0       0                                        175      1.0       1.0       0       0                                        200      6.5       4.0       1.0     0                                        225      11.5      7.5       0.5     0                                        250      25.0      17.5      2.0     1.0                                      275      20.0      15.0      4.5     0.5                                      300      33.0      50.0      5.0     2.0                                      325      0.5       3.5       10.0    4.5                                      350      0.5       0.5       23.0    5.5                                      375      --        0.5       20.0    6.5                                      400      --        0.5       30.5    14.0                                     425      --        --        3.5     16.0                                     450      --        --        --      30.8                                     475      --        --        --      18.0                                     500      --        --        --      2.0                                      ______________________________________                                    

The results of this procedure are graphically illustrated in FIG. 4.

EXAMPLES 13-16 Relation of Baseoil Low Boiling Fractions and VolatileFractions to C₇ Asphaltene Formation

The relationship of baseoil low boiling fractions (as determined bygas-chromatographic distillation), and of baseoil volatile fractions (asdetermined by thermal analysis), to the rate of asphaltene formation canbe expressed by many methods.

One of these methods involves oxidizing baseoils at 300° C., andplotting the formation of low boiling fractions or volatile fractionsagainst the time required to form a carbonaceous material containing 40%of C₇ -asphaltenes. As presented below in Table IV, Examples 13-16illustrate this relationship.

                                      TABLE III                                   __________________________________________________________________________                                  Hours to form                                            Thermal Analysis                                                                        Gas-Chromatographic                                                                      carbonaceous                                         Baseoil                                                                           Volatiles @ 300° C.                                                              Fraction (%) with                                                                        material with 40%                               Example                                                                            Type                                                                              (wt %)    Boiling at 400° C.                                                                of C.sub.7 -asphaltene                          __________________________________________________________________________    13   100 N                                                                             99        40          6                                              14   150 LP                                                                            94        20          6                                              15   600 N                                                                             13         3         11                                              16   150 BS                                                                             3         0         16                                              __________________________________________________________________________

The data presented above in Table III clearly demonstrate therelationship of amounts of low boiling fractions and volatile fractionsin baseoils to coking tendencies. It is thus demonstrated thatasphaltenes are the real precursors of coke formation.

MEASURING EFFECTIVENESS OF BASEOIL ADDITIVE

In co-pending application Ser. No. 876,462, now Pat. No. 4,849,361,attorney docket P4890, entitled "Method of Characterizing CokingTendency of Baseoils", the disclosure of which is incorporated byreference, an inventive method for measuring the effectiveness of abaseoil additive for reducing the onset and/or progression of asphalteneformation in a baseoil is disclosed. In one embodiment, this inventivemethod comprises the steps of:

(a) subjecting a sample of a baseoil to conditions which accelerateasphaltene formation in the baseoil;

(b) testing for the onset and/or progression of asphaltene formation inthe sample of a function of time;

(c) incorporating the additive to be tested into a second sample of thebaseoil;

(d) subjecting this sample to asphaltene formation acceleratingconditions substantially identical to those of step (a);

(e) testing for the onset and/or progression of asphaltene formation inthe additive-containing baseoil of step (c) as a function of time undersubstantially identical conditions to step (b); and

(f) comparing the onset times and/or formation rates measured in steps(b) and (e).

In the second embodiment of the invention, the steps of acceleratingasphaltene formation, and testing for onset and/or progression of saidformation, are replaced by the thermal analysis and gas-chromaticdistillation techniques employed as part of the first embodiment of theinvention, for preparing a blend of predetermined coking tendency.

Broadly stated, the inventive method of the second embodiment of thisinvention involves the steps of:

(a) measuring the amount of volatile fractions, or low boilingfractions, or both, present in the baseoil, to determine the onsetand/or progression of asphaltene formation in the absence of theadditive to be tested;

(b) incorporating the additive to be tested into a sample of thebaseoil, and characterizing the coking tendency of the sample by thesteps of:

I. subjecting the sample to conditions which accelerate asphalteneformation in the baseoil; and

II. testing for the onset and/or progression of asphaltene formation inthe sample as a function of time; and

c. comparing the onset and/or progression of asphaltene formation insteps (a) and (b).

This embodiment of the invention provides the improvement of allowingthe coking tendency of the additive-free baseoil sample to be determinedwithout the necessity of performing the actual acceleration andmeasuring of asphaltene formation.

As for the step of characterizing the coking tendency of the baseoilwith additive added, the acceleration of asphaltene formation can beaccomplished by any one of several means.

One of such means comprises oxidizing and heating the baseoil,preferably by continuous oxidation, at approximately 240°-360° C.

Another means for accelerating asphaltene formation in the additive-freebaseoil comprises subjecting the baseoil to catalytic reaction. Anyappropriate catalyst, such as Freidel-Craft catalyst can be employed.Preferred catalysts include ferric chloride hexahydrate, cobalt octoate,iron naphthenate, stannic chloride, or mixtures of such catalysts. Thecatalyst is preferably employed in total amounts by weight of about0.25% catalyst/fee. The catalytic reaction may be conducted at atemperature of approximately 180°-280° C. A material selected from thegroup consisting of peroxides, hydroperoxides, oxidized lube oils, andmixtures of such materials may also be employed in the catalyticreaction.

While use of a catalytic system does accelerate oxidation, it representsa less accurate simulation of accurate operating conditions, by virtueof the presence of the catalysts, and the use of lower reactiontemperature.

A third means for accelerating asphaltene formation comprises reactingthe baseoil with an effective amount of material selected from the groupconsisting of peroxides, hydroperoxides, oxidized lube oils, andmixtures of such materials.

Any of these three indicated means for accelerating asphaltene formationcan further include sparging the baseoil with an oxidizing gas selectedfrom the group consisting of air, oxygen, ozone, nitrogen oxides (suchas nitric oxide), sulfur oxides, and mixtures of such oxidizing gases.Preferably, the sparging is conducted with air, as 1-10 standard cubicfeet of air per hour. Most preferably, the baseoil is agitated by meansof a mechanical agitator during the sparging.

Further, an inert gas such as nitrogen, carbon dioxide, helium, ormixtures of such gases may be incorporated into the oxidizing gas duringthe sparging.

Although the invention has been described with reference to particularmeans, materials and embodiments, it is to be understood that theinvention is not limited to the particulars disclosed and extends to allequivalents within the scope of the claims.

What is claimed is:
 1. A process for measuring the effectiveness of anadditive for reducing the onset and/or progression of asphalteneformation in a baseoil, said process comprising:(a) measuring the amountof volatile fractions and low boiling fractions present in said baseoilto determine, in the absence of said additive, the onset and/orprogression of asphaltene formation in said baseoil; (b) incorporatingsaid additive into a sample of said baseoil, and characterizing thecoking tendency of said sample by the steps of:I. subjecting said sampleto conditions which accelerate asphaltene formation in said baseoil; andII. testing for the onset and/or progression of asphaltene formation insaid sample as a function of time; and (c) comparing the onset and/orprogression of asphaltene formation in steps (a) and (b).
 2. The processof claim 1 wherein the asphaltene for which the onset and/or progressionof formation is determined is C₇ -asphaltene.
 3. The process of claim 2wherein step (a) comprises:I. measuring the amount of volatile fractionspresent in the said baseoil by the steps of: A. heating, toapproximately 600° C., a sample comprising approximately 0.005 to 1.0gof said baseoil, under an inert atmosphere and in a thermal balance, ata rate of approximately 5° to 20° C./min.; and B. continuously measuringthe weight loss in said sample; and II. measuring the amount of lowboiling fractions present in said baseoil by gas chromatographicdistillation.
 4. The process of claim 3 wherein the heating rate in step(a) I.A. is 10° C./min., and the inert atmosphere comprises nitrogen. 5.The process of claim 2 wherein step (a) comprises: I. measuring theamount of volatile fractions present in said baseoil by the steps of:A.heating, to approximately 1000°, a sample comprising approximately 0.005to 1.0g of baseoil, under an atmosphere selected from the groupconsisting of inert atmospheres and oxidizing atmospheres and in athermal balance, at a rate of approximately 5° to 20° C./min.; and B.continuously measuring the weight loss in said sample; and II. measuringthe amount of low boiling fractions present in said baseoil by gaschromatographic distillation.
 6. The process of claim 4 whereinasphaltene formation is accelerated in step (b) by oxidizing and heatingsaid baseoil.
 7. The process of claim 6 wherein asphaltene formation isaccelerated in step (b) by continuous oxidation at approximately240°-360° C. while sparging said baseoil with an oxidizing gas selectedfrom the group consisting of air, oxygen, ozone, nitrogen oxides, sulfuroxides, and mixtures thereof.
 8. The process of claim 7 comprisingincorporating an inert gas into said oxidizing gas, said inert gas beingselected from the group consisting of nitrogen, carbon dioxide, helium,and mixtures thereof.
 9. The process of claim 7 comprising sparging saidbaseoil in step (b) with air at 1-10 standard cubic feet of air perhour.
 10. The process of claim 7 comprising agitating said baseoilduring said sparging with a mechanical agitator.
 11. The process ofclaim 4 wherein asphaltene formation is accelerated in step (b) bycatalytic reaction of said baseoil.
 12. The process of claim 11 whereinsaid catalytic reaction is performed by exposing said baseoil to acatalyst selected from the group consisting of ferric chloridehexahydrate, cobalt octoate, iron naphthenate, stannic chloride, andmixtures thereof.
 13. The process of claim 12 wherein said catalyticreaction is performed by further exposing said baseoil to a materialselected from the group consisting of peroxides, hydroperoxides,oxidized lube oils,: and mixtures thereof.
 14. The process of claim 12comprising heating said baseoil during said catalytic reaction at atemperature of 180°-280° C.
 15. The process of claim 11 comprisingsparging said baseoil during said catalytic reaction with an oxidizinggas selected from the group consisting of air, oxygen, ozone, nitrogenoxides, sulfur oxides, and mixtures thereof.
 16. The process of claim 15comprising incorporating an inert gas into said oxidizing gas, saidinert gas being selected from the group consisting of nitrogen, carbondioxide, helium, and mixtures thereof.
 17. The process of claim 4wherein asphaltene formation is accelerated in step (b) by reacting saidbaseoil with a material selected from the group consisting of peroxides,hydroperoxides, oxidized lube oils, and mixtures thereof.
 18. Theprocess of claim 17 comprising sparging said baseoil during saidreaction with an oxidizing gas selected from the group consisting ofair, oxygen, ozone, nitrogen oxides, sulfur oxides, and mixturesthereof.
 19. The process of claim 18 comprising incorporating an inertgas into said oxidizing gas, said inert gas being selected from thegroup consisting of nitrogen, carbon dioxide, helium, and mixturesthereof.